This is a major investigation regarding possible evidence of adverse health effects attributable to dental amalgams in a specific adult male population. The NIDR Amalgam Study involves 1166 Air Force male Veterans, representing a 50% subsample of the Air Force Health Study participants. These participants were examined for scores of medical conditions, including many which would be potentially affected by exposure to mercury vapor. Dental examinations and blood and urine samples were obtained. The exact exposure to amalgams was defined as the total number of surfaces with an amalgam. All soft tissue conditions present were obtained. Mercury levels in blood and urine were recorded as mu g/l. Amalgam exposure for this cohort was determined to be rather high, averaging 20 surfaces per person. The blood and urine Hg levels were found to be low, averaging 3.09 mu g/l for urine and 2.55 mu g/l in blood. There were less than a dozen subjects who had Hg levels higher than 15 mu g/l, and among these subjects the levels could not be attributable to amalgams. There was a clear association (r = 0.34) found between amalgam exposure and urinary Hg levels. A significant association was also detected for blood levels (r = 0.09), but was considered as clinically irrelevant. The health data are currently under analysis. The neurological findings will be reported in the next few months.